Staybolt and method of manufacturing the same



Patented .lune 1938 STYBOLT AND METHOD oF MANUFACTUR- ING THEv SAME,

William` B. Peirce, Pittsburgh, and Nicholas J. Kouche, Bridgeville,Pa., assignors to Flannery Bolt Companyridgeville, Ea., a corporation ofDelaware .Y Application May 11, 1936, SerialmNo."79,026

5 claims. (c1. 111-275 invention relates' to staybolts and their`manufacture, and more particularly to the form and manufacture of whatis known as a rigid `staybolt with a square head.

l Theusual form of a'finished rigid staybolt is a round bar or blankwith a square head being used to hold the bolt during the threadingoperation and also used to screw the finished bolt in the boiler duringthe installation' operation. As the object of a staybolt is to supportthe outer and kinner sheets ofa boiler or to keep them from A spreadingunder pressure it is obvious that it must be tightly screwed and rivetedin the boiler sheets to prevent leakage and to have the necesl5 sarysustaining strength.

In order to make a staybolt fit neatly in the tapped holes of a boilerthe threads .must be ac- `curately cut and perfect in shape, especiallythe tops of the rthreads must be fully formed. If, in

zo the process vof threading, a rigid Astaybolt is not held perfectlyconcentric with the threading dies, thenthe dies will cut too much offon oneside and not leave enough material on the opposite side to make afull thread.

In theathreading of a rigid staybolt where the thread must be perfect inshape right upto the Isquare head it is necessary in commercial thread-.ing to hold the bolt on the square head. If the head is not concentricwith the body then the -body willnot be concentric with the die and thethread will not be perfect in form. A head that is non-concentricwiththenished body of a rigid .bolt has a. tendency to wobble the bolt whenit is being screwed in the boiler plates with a motor driven squaresocket. This wobbling sometimes keeps the bolt from entering the secondboiler sheet after screwing through the first sheet.

` Heretofore in the manufacture of rigid staybolts it has beenzthe usualpractice to out the commercial bar of staybolt iron into lengths andthen either hot forge or cold press the square on one end, and thenthread the bolt its entire length by holding it by the square while thedie cuts the thread. It is almost impossibley to commercially make a hotforged square on a bolt blank that is exactly concentric with the body,and the cold pressing of the square doesnot always make the squaresconcentric even if the dies are in perfect shape. In either hot forged4or cold pressed squaring a rough shoulder lis left between the "5A'.Squaredportion and' the' rest of the bolt which varies in lengthaccording to diameter of the bolt "being squared. :This rough lshoulderis neither square nor. round and is` therefore a lost nl `length as thethread. cut. on it is not fully formed.

venough'stock` to make a good square.

Usually the size of the squares on all rigid staybolts are of the samesize'regardless of the diameter of the bolt. To make a good square of astandard dimension by the cold press process required a certain diameterof iron regardless of 5 what diameter the bolt happens to be, then theend'of all rigid bolts requiring a standard square should be the same orstandard diameter regardrless ofthe diameter of the body of the bolt. Itis obvious that if this standard diameter to make a-m standard square ismaintained for all diameters of bolts, the body diameter of large boltsmust` be reduced tof this standard diameter for a length long enough tomake the square. This has been customarypractice, but usually is done bya sepy 15 arate operation. j l,

According to the present invention, an annular kerf is vcut into theblank stock at the time the blank stock is parted from the commercialbar on a parting machine. This-kerf is a distancezo from the end of theblank which allows just As the kerf is cut vduring the parting operationno extra time is required and when `a forming or shaving tool is usedbetween the parting and kerfing tool thisz5 portion of the bolt body maybe reduced to` ther proper diameter to make a good standard squareWithout any extra time over the parting operaftion. Both ends of thebolt blank may also be chamfered by using a chamfering tool in combi-3.0

nation with the parting, kerfing and formingL tools without yany loss oftime. The kerf is ordinarily cut to a depth making its diameter equal orslightly under the flats of thesquare to be put on. This kerf leaves aclean-cut shoulder on the 35 body of the bolt capable of receiving aclean-cut vthread of fullv size, and an accurate termination of thethread of the bolt, also an accurate termi. nation of the square end anditsv width is allowed to be computed as part of the square length, thus,40 eliminating the lost length due to the rough shoulder made by theordinary squaring process. When a bolt blank with a formed end of theproper size' and a kerf cut to the proper depth at a proper distancefrom the end of theblank is 415 subjected to the squaring dies itproduces a good square, concentric with the body of the bolt.

`This then allows a perfect thread to `be cut on the blank clear up tothe kerf shoulder. By reasonv of the cutting kerf the cold working doesnot o 50 extend back into the threaded section of the bolt.r

The invention may readily be understood by reference to the accompanyingdrawing, in which:

Figure 1 indicates moreor less diagrammatically, the. step in theprocess", of manufacturingv .the 5.5

bolt wherein one length of stock is being cut off or parted from a rodwhile the next adjoining length of stock is having a kerf formed thereinand the portion for the square formed to size.

Figure 2 is a side elevation of a portion of the blank showing the headend thereof in its proper shape.

Figure 3 is a similar view showing the blank after the head end had beensquared.

Figure 4 is an end View of the completed bolt.

Figure 5 is a side elevation of the completed bolt.

Figure 6 is a side elevation of the head end of a slightly modified formof bolt.

Figure 7 is a perspective view illustrating one of two dies which areused in forming the square on the boit.

Referring to Figure 1, A ldesignates a piece of stock of indefinitelength which is in the process of being cut up into blanks. B indicatesa blank which is almost cut off, the cutting tool for severing the blankB from the length of` stock A being designated C. D represents a cuttingtool maintained in predetermined spaced relation to cutter C for cuttinga kerf in the stock A, a predetermined distance back from cutter C. Frepresents the portion of the bolt to be made into a square. If thediameter of the stock is such that the portion F has to be reduced tobring the diameter down to a diameter necessary to make a square head ofstandard size, a third cutter for turning down the diameter o-f portionF may be provided between cutters C and D. In this cutting operation itmay be assumed that the rod A is being turned by some suitable chuck notshown. After the blank B has been completely cut off the support E onwhich the cutters are carried is moved transversely away from the stock,the stock advanced the necessary length to form a blank, and theoperation is again repeated, the length of stock A thus beingsuccessively out into blanks, each blank when it is completed having aportion for a head and a kerf formed therein a predetermined distancefrom one end thereof, such head portion also being reduced wherenecessary.

This is clearly illustrated in Figure 2 wherein the blank B has a kerfdesignated 2 therein, a head forming portion 3 between the kerf and theend of the blank. In this figure, as distinguished from Fig. 1, we haveshown the head portion reduced in diameter to the extent necessary toform a good square head of standard dimension. The body of the blank isdesignated 4. The body 4 has the original diameter of the stock A whilethe portion 'is, as is usually the case, of smaller diameter. The kerf 2is of such depth that the diameter of the neck portion 5 connecting thebody Il with the portion 3 is substantially the same or slightly lessthan the ats of the square head which is subsequently formed.

If the blank shown in Figure 2 has the head forming portion 3 formedinto a square by being pressed between two dies as shown in Figure 7,the body portion being laid in the semi-circular part of the die 'l andthe head forming portion 3 in the square part of the die then the formedblank, as shown in Figure 3, will be produced. This die is of the typenow generally used in the manufacture of staybolts, and forms no part ofthe present invention per se. The square head thus formed by beingpressed between two dies as shown in Figure 7 is more perfectly formedon a blank with a kerf for the reason that the metal is allowed to flowlongitudinally in both directions and as the portion that is to besquared is of the proper diameter regardless of the diameter of thebody, the square made therefrom is as nearly perfect as can commerciallybe made, and as the squaring die does not have to shear the bodydiameter of the bolt'down to the square size, the concentratingand'alignment is more easily maintained.

Figure 3 clearly illustrates a blank that has been squared, showing thesquare shoulder made by the kerf, while Figure 4 shows an end View ofthe same bolt.

Figure 5 shows the side elevation of a finished bolt showing theclean-cut threads right up to the shoulder made by the kerf and alsothat the length of the square can be computed from this shoulder. Toinstall a rigid staybolt in a boiler it first must be screwed throughboth boiler sheets and just enoughof the threaded portion left toproject past the face of the sheet to rivet over. The riveting processupsets the bolt in its threaded hole and forms a slight button head thatseals the joint between the bolt and the boiler sheet. It is obviousthen that the square head must be removed after the bolt is screwed inplace, the square then having served its full function. The removal ofthe square head is sometimes done by breaking it off, and in such casesit is sometimes desirable to facilitate the breaking by what is commonlyknown as necking in or nicking the head. This is illustrated in Figure 6where the neck portion 8 is of less diameter than the thickness of thehead portion 9 and the threaded body of the bolt lll. 'Ihis neck issufficiently strong to withstand the torque of both threading the boltand of screwing it into place, but facilitates the severing of the headafter` the bolt has been screwed into place. This extra deep kerf can becut in the same way as the standard depth of kerf and does not requireany more time or expense.

By the practice of the present invention, bolts of better appearance andgreater accuracy are produced. All of them are of uniform appearance andall have a full thread up to the kerf'. The head forming is effectedwith less distortion of the metal, and the effect of cold working isconned to the head and does not extend into the body of the bolt. Lesswork has to be performed by the dies, so that the operation is performedmore easily and with less wear on the dies. The method, moreover,enables the blank to be initially a fraction of an inch shorter thanwith' methods heretofore employed, and this results in a further economyto the manufacturer.

We claim: l

1. The method of forming a staybolt which comprises forming a blank ofround metal stock, producing an annular kerf in said stock adjacent oneend thereof thereby dividing the blank into a body portion and a headportion connected by an intervening neck portion of reduced diameter,and subsequently forging the head portion to produce a square headhaving a diameter less than the diameter of the body portion andsubsequently threading the body portion of the blank.

`2. The method of making staybolts which comprises producing a blank ofround metal stock having a kerf therein adjacent one end thereof, saidkerf dividing the blank into a body portion and a head-forming portionconnected by a neck portion of reduced diameter, and subsequentlypressing the head-forming portion of the blank to a square shape thetransverse yus thickness of which is not substantially less than thediameter of the neck portion.l y

3. The method of making staybolts which comprises producing a blank ofround metal stock having a kerf therein adjacent one end thereof, saidkerf dividing the blank into a body portion and a head-forming portionconnected by a neck portion of reduced diameter, and subsequentlypressing the headfformingportion of the blank to a square shape thethickness of which is some what greater than the diameter of the neckportion. Y

4. In the manufacture of staybolts from a length of round stock, thesteps Which comprise simultaneously cutting ,the stock into lengthsy andforming on each length an annular kerf near one end of the blank wherebythe blank is ldivided into a body portion and a head-forming portionconnected by a neck portion of smaller diameter than the body or headportion, pressing the headforming portion to a substantially squarecrosssection the thickness of Whichv is substantially less than theoutside diameter of the body pore tion, and thereafter threading thebody portion.`

5. A staybolt comprising a threaded body portion, a forged head portionand a circular neck portion connecting the head and body portions, saidneck portion being of less diameter than the threaded body portion andhaving substantially the original grain of the metal blank from whichthe bolt is formed. WILLIAM B. PEIRCE.

NICHOLAS J. KOUCHE.

